Hydrogen has been utilized in various fields in industry. Specifically, hydrogen has been used as raw materials, for example, in production of ammonia by the Haber-Bosch process, production of hydrochloric acid by photoreaction with chlorine gas, and modification of oil and fat, such as corn oil and cotton oil, by adding hydrogen thereto for hydrogenation (hardening), and as reducing agents, for example, in reduction of metallic minerals (oxides), production of aniline by reducing nitrobenzene, catalytic reduction of benzene in production of nylon 66, synthesis of methyl alcohol by reducing carbon monoxide, and desulfurization.
Furthermore, hydrogen does not form wastes, such as particulate emissions and exhaust gas, e.g., carbon dioxide, other than water on combustion, and thus is being expected as alternate energy. A hydrogen-fueled car having a hydrogen-fueled engine as an internal combustion engine is commercially available, and hydrogen is used as a rocket fuel and in a fuel cell.
Hydrogen is mass-produced industrially as a by-product of steam reformation and partial oxidation of a hydrocarbon (i.e., the hydrocarbon gas decomposition method). In the method, methane gas in natural gas, paraffin compounds, ethylene or propylene is decomposed into hydrogen and carbon monoxide by reacting with steam with nickel as a catalyst at a high temperature, and carbon monoxide thus by-produced is further reacted with steam to form carbon dioxide and hydrogen gas. As an alternate method, such hydrogen may be utilized that is formed as a by-product of electrolysis of seawater in soda industry and salt production.
Hydrogenation reaction where hydrogen is reacted with an organic compound is being widely used in organic synthetic chemistry, and various useful compounds are formed by the method. Various types of hydrogenation reaction have been known, such as reaction utilizing an alkali metal or the like, reaction utilizing a metal hydride or a metal hydrogen complex, reaction utilizing diborane or hydrazine, reaction utilizing catalytic hydrogenation, and the like.
However, the industrial production methods of hydrogen described above require large-scale equipment and cannot be utilized for convenient production of hydrogen gas. There is an experimental method of utilizing hydrogen gas that is generated by dissolving a metal in a diluted acid or an alcohol, but the method has problems in that a metal is irreversibly dissolved, and a solution formed by dissolving a metal is necessarily treated.
Furthermore, in the hydrogenation reactions described above, the methods using an alkali metal, a metal hydride, a metal hydrogen complex, diborane and hydrazine have a problem of high cost of the reagents used and a problem of risks of the reagents. The method utilizing catalytic hydrogenation also has a problem in that a special metal catalyst is necessarily used.